Lowering Odds of Multiple Births, New York Times, Febbruary 19, 2008:
“Now is the time for all of us to rethink what is the paradigm of a successful I.V.F. pregnancy,” said Dr. Aaron K. Styer, a reproductive endocrinologist at the Massachusetts General Hospital Fertility Center in Boston. “Is it a pregnancy without regard to the number of gestations or a pregnancy with a singleton live birth?”Da leggere tutto. Se aveste la memoria corta in Italia è obbligatorio impiantare tutti e 3 gli embrioni prodotti e le linee guida, scadute la scorsa estate, aspettano un nuovo vestito. Che non si annuncia di certo rivoluzionario. La speranza si concentra sul divieto della diagnosi genetica di preimpianto. Ma molte speranze vanno deluse; perciò nessun entusiasmo affrettato.
In I.V.F., a woman is given ovulation-induction hormones to produce multiple eggs, which are retrieved, fertilized with her partner’s sperm and transferred back to her uterus. The more embryos transferred, the higher the likelihood of multiples.
To achieve the goal of a single healthy baby, clinics are focusing on transferring fewer embryos and on developing more sophisticated ways to identify the healthiest embryos with the greatest chance of success.
“We have been getting better at I.V.F. over the years, and as success rates go up, the number we transfer has to go down accordingly,” said Dr. Judy E. Stern, director of the human embryology and andrology lab at the Dartmouth-Hitchcock Medical Center in Lebanon, N.H. “Where three embryos used to work and give you mostly singletons, now we transfer two, because we’re making better embryos and more of them implant.”